Apparatus and method for manufacturing carbon nanotubes

ABSTRACT

An exemplary apparatus includes a reaction chamber having a gas inlet at a lower portion thereof configured for introducing a carbon source gas thereinto and a gas outlet at an upper portion thereof, the reaction chamber defining a carbon source gas flow route, a substrate holder arranged between the gas inlet and gas outlet in the reaction chamber, and at least one substrate having a number of through holes defined therein configured for facilitating the flowing of the carbon source gas therethrough and a catalyst layer formed on a surface thereof facing the gas inlet, the at least one substrate being positioned on the carbon source gas flow route by the substrate holder.

TECHNICAL FIELD

The present invention relates to apparatuses and methods for manufacturing carbon nanotubes, and particularly to an apparatus and method for manufacturing carbon nanotubes by a chemical vapor deposition method.

DISCUSSION OF RELATED ART

Carbon nanotubes are tubules of carbon generally having a length of 5 to 100 micrometers and a diameter of 5 to 100 nanometers. Carbon nanotubes are composed of a number of co-axial cylinders of graphite sheets and have recently received a great deal of attention for use in different fields such as field emitters, gas storage and separation, chemical sensors and high strength composites. Carbon nanotubes have many promising properties such as a high strength and low weight, high energy and fuel storage capability, good electron emission capability and many advantageous thermal, chemical and surface properties.

Currently there are three principal methods to manufacture carbon nanotubes, namely arc discharge, laser ablation and chemical vapor deposition. Among these, the chemical vapor deposition method is perhaps most widely used.

A general apparatus for manufacturing carbon nanotubes with a chemical vapor deposition method includes a reaction furnace and a substrate with a catalyst layer thereon in the reaction furnace. A process for manufacturing carbon nanotubes with above-described apparatus includes the steps of:

(1) providing a substrate with a catalyst layer and placing it in the reaction furnace;

(2) heating the reaction furnace to a predetermined temperature;

(3) supplying a carbon source gas into the reaction furnace and growing carbon nanotubes by a chemical vapor deposition method.

Such a manufacturing process suffers from the disadvantage that the growth direction of carbon nanotubes is affected by the flow direction of the gas, so the alignment of carbon nanotubes is not good.

What is needed, therefore, is an apparatus and method for manufacturing aligned carbon nanotubes.

SUMMARY

An apparatus and method for manufacturing aligned carbon nanotubes according to a preferred embodiment is provided.

The apparatus includes a reaction chamber having a gas inlet at a lower portion thereof configured for introducing a carbon source gas into the reaction chamber with a gas outlet in an upper portion thereof, the reaction chamber defining a carbon source gas flow route, a substrate holder arranged between the gas inlet and gas outlet in the reaction chamber, and at least one substrate having a number of through holes defined therein configured for facilitating the flow of carbon source gas therethrough and a catalyst layer formed on a surface thereof facing the gas inlet, the at least one substrate being positioned in the carbon source gas flow route by the substrate holder.

The method includes the steps of:

(a) providing a substrate having a number of through holes defined therein and a catalyst layer formed on a first surface thereof;

(b) orienting and positioning the substrate in a manner such that the first surface of the substrate faces downwardly;

(c) supplying and directing a carbon source gas to flow vertically from the first surface to an opposite second surface of the substrate for growing carbon nanotubes thereon by a chemical vapor deposition method.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and advantages of the present apparatus and method for manufacturing carbon nanotubes, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments thereof taken in conjunction with the accompanying drawings.

FIG. 1 is a schematic, front view of an apparatus for manufacturing carbon nanotubes in accordance with a first preferred embodiment of the present invention;

FIG. 2 is schematic, top view of a substrate of the apparatus in accordance with the first preferred embodiment of the present invention;

FIG. 3 is a schematic, front view of an apparatus for manufacturing carbon nanotubes in accordance with a second preferred embodiment of the present invention;

FIG. 4 is schematic, top view of a substrate holder of the apparatus in accordance with the second preferred embodiment of the present invention.

FIG. 5 is schematic, top view of a substrate of the apparatus in accordance with the second preferred embodiment of the present invention.

FIG. 6 is a schematic, front view of an apparatus for manufacturing carbon nanotubes in accordance with a third preferred embodiment of the present invention; and

FIG. 7 is schematic, top view of a substrate of the apparatus in accordance with the second preferred embodiment of the present invention.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate at least one preferred embodiment of the present apparatus and method for manufacturing carbon nanotubes, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference will now be made to the drawings to describe in detail the preferred embodiments of the present apparatus and method for manufacturing carbon nanotubes.

Referring to FIG. 1, an apparatus 100 for manufacturing carbon nanotubes according to a first preferred embodiment is shown. The apparatus 100 includes a reaction chamber 110, a heating device 120, and a substrate 130.

The reaction chamber 110 has a gas inlet 112, a gas outlet 114 and a substrate holder 116. The gas inlet 112 is configured at a bottom of the reaction chamber 110 for introducing a carbon source gas into the reaction chamber 110. The gas outlet 114 is configured at a top of the reaction chamber 110 for outputting gas. Preferably, the gas outlet 14 is directly opposite to the gas inlet 112, thus a reaction gas input from the gas inlet 112 can flow directly from the bottom of the reaction chamber 110 to the top of the reaction chamber 110. The substrate holder 116 is arranged between the gas inlet 112 and gas outlet 114 in the reaction chamber 110 for holding the substrate 130. As such, the reaction gas can flow through an area for holding the substrate 130 in a direction substantially parallel to a growth direction of carbon nanotubes.

The heating device 120 is configured adjacent the reaction chamber 110 for heating the reaction chamber 110. In this embodiment, the heating device 120 is disposed around the reaction chamber 110. The heating device 120 may be high temperature furnace, high frequency furnace etc.

The substrate 130 is held on the substrate holder 116.

Referring to FIG. 2, the substrate 130 defines a number of through holes 132 for facilitating the flowing of reaction gas therethrough. The through holes 132 can be distributed irregularly or regularly in the substrate 130. A diameter of each of the through holes 132 may be in a range from 0.5 microns to 1 micron. A catalyst layer 134 is formed on a surface of the substrate for growing carbon nanotubes. The catalyst layer 134 can be composed of a catalyst material used for growth of carbon nanotubes, such as iron, cobalt, nickel etc.

A method for manufacturing carbon nanotubes using the apparatus 100 according to an aspect of present invention includes the steps in no particular order of:

(a) a substrate 130 is provided, and a number of the through holes 132 are defined therein and a catalyst layer 134 is formed on a first surface thereof;

(b) the substrate 130 is oriented and positioned in a manner such that the first surface of the substrate 130 faces downwardly;

(c) a carbon source gas is supplied and directed to flow vertically from the first surface to an opposite second surface of the substrate 130 for growing carbon nanotubes thereon by a chemical vapor deposition method.

In the step (a), the through holes 132 can be made using a photolithography method, and in the present embodiment they are formed using a drilling method. A diameter of each of the through holes 132 is in a range from 0.5 microns to 1 micron. The catalyst layer 134 can be formed using a method selected from the group consisting of ion plating, radio frequency magnetron sputtering, vacuum evaporation, and chemical vapor deposition.

In the step (b), the first surface of the substrate 130 faces downwardly so as to make the growth direction of carbon nanotubes consistent with gravitational pull.

In the step (c), the catalyst layer 134 is first heated to 500˜900° C. with a heating device 120 such as high temperature furnace or high frequency furnace around the reaction chamber 110; a mixed gas including carbon source gas such as methane, acetylene, ethylene, carbon monoxide or a mixture thereof and protective gas such as helium, argon, hydrogen, or ammonia are then supplied; the carbon source gas is cracked at the catalyst layer 134 to grow carbon nanotubes.

Referring to FIGS. 3-5, an apparatus 200 for manufacturing carbon nanotubes according to a second embodiment is shown. Similar to the apparatus 100 of the first embodiment, the apparatus 200 includes a reaction chamber 210 and a heating device 220 around the reaction chamber 210, wherein the reaction chamber 210 defines a gas inlet 212 configured at a bottom of the reaction chamber 210 and a gas outlet 214 configured at a top of the reaction chamber 210. The difference between apparatus 200 and apparatus 100 is that the substrate holder 216 has a post 2162 extending upwardly for supporting a number of substrates 230 thereon and a number of through holes 2164 aligned therein with respect to the through holes 232 of the substrates 230 in an area opposite to the at least one substrate for facilitating reaction gas therethrough, and a number of washers 400 surrounding the post 2162 to separate the substrates 230 from each other. Each of the substrates 230 has an engaging hole 236 spatially corresponding to the post 2162. As such, the substrates 230 are secured to the substrate holder by extension of the post 2162 through the engaging hole 236.

A method for manufacturing carbon nanotubes with the apparatus 200 of the second preferred embodiment is described in detail as follows:

(1) a number of substrates 230 are provided, and a engaging holes 236 and a number of through holes 232 arc formed in each of the substrates 230, and a catalyst layer 234 formed on a first surface of each of the substrates 230;

(2) the substrates 230 are placed on the substrate holder 216;

(3) a carbon source gas is supplied into the reaction chamber 210 through the gas inlet 212 from bottom to top and growing carbon nanotubes by a chemical vapor deposition method.

In the step (2), the substrates 230 are secured to the substrate holder 216 by the post 2162 of the substrate holder 216 extending through the engaging hole 236 in series with a predetermined space, and the substrates 230 are spaced apart from each other. Generally the space is greater than the growth height of carbon nanotubes. In the present embodiment, the substrates 230 are spaced from each other by a number of washers 400. The catalyst layer 234 of each of the substrates 230 faces the gas inlet 212 to make the growth direction of carbon nanotubes consistent with gravitational pull.

Referring to FIG. 6 and FIG. 7, an apparatus 300 for manufacturing carbon nanotubes according to a third embodiment is shown. Similar to the apparatus 100 of the first embodiment, the apparatus 300 includes a reaction chamber 310 and a heating device 320 around the reaction chamber 310, wherein the reaction chamber 310 defines a gas inlet 312 configured at a bottom of the reaction chamber 310 and a gas outlet 314 configured at a top of the reaction chamber 310. However, the substrate holder 316 has a couple of posts 3162 extending upwardly for supporting a number of substrates 330 thereon, and a number of washers 500 surrounding each of the posts 2162 to separate the substrates 230 from each other. Each of the substrates 330 has a couple of engaging holes 336 for engaging a corresponding couple of posts 3162. As such, the couple of posts 3162 can extend through the engaging holes 336 so as to hold the substrates 330 thereon.

A method for manufacturing carbon nanotubes with the apparatus 300 of the third preferred embodiment is described in detail as follows:

(1) a reaction chamber 310 having a gas inlet 312 and a gas outlet 314 at a bottom and a top thereof respectively is provided, a substrate holder 316 arranged therein, and the substrate holder 316 having a couple of posts 3162;

(2) a number of substrates 330 are provided, and a couple of engaging holes 336 and a number of through holes 332 are formed in each of the substrates 330, and a catalyst layer 334 is formed on a surface of each of the substrates 330;

(3) the substrates 330 are placed on the substrate holder 316;

(4) a carbon source gas is supplied into the reaction chamber 310 through the gas inlet 312 from bottom to top and growing carbon nanotubes by a chemical vapor deposition method.

In the step (3), The substrates 330 are secured to the substrate holder 316 by the post 3162 of the substrate holder 316 extending through the engaging hole 336 in series with a predetermined space, and the substrates 330 are spaced apart from each other. Generally the space is greater than the growth height of carbon nanotubes. In the present embodiment, the substrates 330 are spaced from each other by a number of washers 500. The catalyst layer 334 of each of the substrates 330 faces the gas inlet 312 to make the growth direction of carbon nanotubes consistent with gravity direction of that

An advantage of the above-described apparatuses are that the catalyst layer of the substrates face the gas inlet and are orientated with the flow direction of the carbon source gas so as to manufacture aligned carbon nanotubes under gravity.

Another advantage of the above-described apparatuses are that a number of substrates having a number of through holes therein can be spaced on the substrate holder according to a predetermined space so as to mass-produce aligned carbon nanotubes.

While the present invention has been described as having preferred or exemplary embodiments, the embodiments can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the embodiments using the general principles of the invention as claimed. Furthermore, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and which fall within the limits of the appended claims or equivalents thereof. 

1. An apparatus for manufacturing carbon nanotubes, comprising: a reaction chamber having a gas inlet at a lower portion thereof configured for introducing a carbon source gas thereinto and a gas outlet at an upper portion thereof, the reaction chamber defining a carbon source gas flow route; a substrate holder arranged between the gas inlet and gas outlet in the reaction chamber; and at least one substrate having a plurality of through holes defined therein configured for facilitating the flowing of the carbon source gas therethrough and a catalyst layer formed on a surface thereof facing the gas inlet, the at least one substrate being positioned on the carbon source gas flow route by the substrate holder.
 2. The apparatus as described in claim 1, wherein the at least one substrate is oriented perpendicular to the carbon source gas flow route.
 3. The apparatus as described in claim 1, wherein a diameter of each of the through holes is in a range from 0.5 microns to 1 micron.
 4. The apparatus as described in claim 1, wherein the substrate holder comprises at least one post, and the at least one substrate defines at least one engaging hole, the at least one substrate is secured to the substrate holder by extension of the at least one post through the at least one engaging hole.
 5. The apparatus as described in claim 1, wherein the substrate holder defines a plurality of through holes aligned with respect to the through holes of the at least one substrate.
 6. A method for manufacturing carbon nanotubes, the method comprising the steps of: (a) providing a substrate having a plurality of through holes defined therein and a catalyst layer formed on a first surface thereof; (b) orienting and positioning the substrate in a manner such that the first surface of the substrate faces downwardly; (c) supplying and directing a carbon source gas to flow vertically from the first surface to an opposite second surface of the substrate for growing carbon nanotubes thereon by a chemical vapor deposition method.
 7. The method as described in claim 6, wherein the carbon source gas is comprised of a material selected from the group consisting of methane, acetylene, ethylene, carbon monoxide and a mixture thereof.
 8. The method as described in claim 6, wherein the through holes of the substrate are defined by a photolithography method.
 9. The method as described in claim 8, wherein the through holes of the substrate are defined by a drilling method.
 10. The method as described in claim 6, wherein a diameter of each of the through holes is in a range from 0.5 microns to 1 micron.
 11. The method as described in claim 6, wherein the catalyst layer is formed by a method selected from the group consisting of ion plating, radio frequency magnetron sputtering, vacuum evaporation, and chemical vapor deposition.
 12. The method as described in claim 6, wherein the catalyst layer is comprised a material selected from the group consisting of iron, cobalt, nickel, and any appropriate combination alloy thereof.
 13. A method for manufacturing carbon nanotubes, comprising the steps of: (a) providing a reaction chamber having a gas inlet and a gas outlet at a bottom and a top thereof respectively and a substrate holder arranged therein, and the substrate holder having at least one post; (b) providing a plurality of substrates each having at least one engaging holes, a plurality of through holes defined therein and a catalyst layer formed on a surface thereof; (c) placing the substrates on the substrate holder with the catalyst layer facing the gas inlet and the at least one post of the substrate holder extending through the at least one engaging holes of the substrates, the substrates being spaced apart from each other; (d) supplying a carbon source gas into the reaction chamber through the gas inlet for growing carbon nanotubes by a chemical vapor deposition method.
 14. The method as described in claim 13, wherein the substrate holder defines a plurality of through holes aligned with respect to the through holes of the at least one substrate.
 15. The method as described in claim 13, wherein the carbon source gas is comprised of a material selected from the group consisting of methane, acetylene, ethylene, carbon monoxide and a mixture thereof.
 16. The method as described in claim 13, wherein the substrates are spaced from each other by a plurality of washers.
 17. The method as described in claim 13, wherein a diameter of each of the through holes is in the range from 0.5 microns to 1 micron.
 18. The method as described in claim 13, wherein the catalyst layer is formed by a method selected from the group consisting of ion plating, radio frequency magnetron sputtering, vacuum evaporation, and chemical vapor deposition.
 19. The method as described in claim 13, wherein the catalyst layer is comprised of a material selected from the group consisting of iron, cobalt, nickel, and any combination alloy thereof. 